Theorem tbtru 1494

Description: A proposition is equivalent to itself being equivalent to T.. (Contributed by Anthony Hart, 14-Aug-2011.)

Assertion

Ref	Expression
tbtru	|- ( ph <-> ( ph <-> T. ) )

Proof of Theorem tbtru

Step	Hyp	Ref	Expression
1		tru 1487	. 2 |- T.
2	1	tbt 359	1 |- ( ph <-> ( ph <-> T. ) )

Syntax hints:   <-> wb 196   T. wtru 1484

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 197  df-tru 1486

This theorem is referenced by:  falbitru  1521  tgcgr4  25426  sgn3da  30603  aistia  41064